M3A1 Submachine Gun 'Grease Gun'

Surplus WWII era weapons were supplied by the United States to various units during the Vietnam War, including the CIDG and PRU. The fully automatic .45 Caliber M3A1 Submachine Gun was first produced in 1945 and resembled a mechanic’s grease gun. Constructed entirely of steel it weighed 7.8 pounds without the sling and magazine, 1.3 pounds heavier than the M16A1 rifle.

It was fed by a 30-round magazine and boasted a cyclical firing rate of 350 to 460 rounds per minute. The M3A1 also featured a telescopic stock, which could be removed and used as a cleaning rod, a wrench and to load the magazine.